Manuscript Becker III.8.43. owned by the Sachsische Landes- und Universitatsbibliothek contains 4 fugues by Johann Ludwig Krebs. The scribe made lots of errors in his transcriptions. So it is a bit of a guess sometimes what is actually meant. The last of these four is the fugue in f minor, KrebsWV 429. It is sort of a double fugue, in which subject and countersubject are played together right from the first entry in the exposition. Later the theme appears in inversion in the pedals, and in stretto in the two lower voices. Krebs does not master counterpoint well enough to be able to weave the counter subject in as well.
The recording was done with the Hauptwerk software and the sampleset, made by Voxus, of the Müller organ in the Sint Bavokerk, Haarlem (http://www.voxusorgans.com/en/product/haarlem).
Score available here: http://partitura.org/index.php/johann-ludwig-krebs-fuga-f-moll-krebswv-429